LT3497 Dual Full Function White LED Driver with Integrated Schottky Diodes FEATURES DESCRIPTION Drives Up to 12 White LEDs (6 in Series per The LT 3497 is a dual full function step-up DC/DC con- Converter) from a 3V Supply verter speci cally designed to drive up to 12 white LEDs Two Independent Boost Converters Capable of (6 white LEDs in series per converter) from a Li-Ion cell. Se- Driving Asymmetric LED Strings ries connection of the LEDs provides identical LED currents Independent Dimming and Shutdown Control of the resulting in uniform brightness and eliminating the need Two LED Strings for ballast resistors and expensive factory calibration. High Side Sense Allows One Wire Current Source The two independent converters are capable of driving per Converter asymmetric LED strings. Accurate LED dimming and Internal Schottky Diodes shutdown of the two LED strings can also be controlled Open LED Protection (32V) independently. The LT3497 features a unique high side LED 2.3MHz Switching Frequency current sense that enables the part to function as a one 5% Reference Accuracy wire current source one side of the LED string can be V Range: 2.5V to 10V IN returned to ground anywhere, allowing a simpler 1-wire TM Dual Wide 250:1 True Color PWM Dimming LED connection. Traditional LED drivers use a grounded Requires Only 1F Output Capacitor per Converter resistor to sense LED current, requiring a 2-wire connec- Available in a 3mm 2mm 10-Pin DFN Package tion to the LED string. The 2.3MHz switching frequency allows the use of tiny APPLICATIONS inductors and capacitors. Few external components are Cellular Phones needed for the dual white LED Driver: open-LED protection PDAs, Handheld Computers and the Schottky diodes are all contained inside the 3mm Digital Cameras 2mm DFN package. With such a high level of integra- MP3 Players tion, the LT3497 provides a high ef ciency dual white LED GPS Receivers driver solution in the smallest of spaces. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. True Color PWM is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. TYPICAL APPLICATION Li-Ion Power Driver for 4/4 White LEDs Ef ciency V 80 IN V = 3.6V 3V TO 5V IN 4/4LEDs 75 1F 15H 15H 70 65 SW1 V SW2 IN CAP1 CAP2 60 LT3497 10 10 1F 1F LED1 LED2 55 CTRL1 GND CTRL2 3497 TA01a 50 OFF ON OFF ON 0 510 15 20 SHUTDOWN SHUTDOWN LED CURRENT (mA) 3497 TA01b AND DIMMING AND DIMMING CONTROL 1 CONTROL 2 3497f 1 EFFICIENCY (%)LT3497 ABSOLUTE MAXIMUM RATINGS PACKAGE/ORDER INFORMATION (Note 1) Input Voltage (VIN) ...................................................10V TOP VIEW SW1, SW2 Voltages ..................................................35V 1 10 LED1 CAP1 CAP1, CAP2 Voltages ................................................35V 2 9 CTRL1 SW1 CTRL1, CTRL2 Voltages ............................................10V 3 11 8 GND V IN 4 7 CTRL2 SW2 LED1, LED2 Voltages ................................................35V 5 6 LED2 CAP2 Operating Temperature Range ................. 40C to 85C Maximum Junction Temperature .......................... 125C DDB PACKAGE 10-LEAD (3mm 2mm) PLASTIC DFN Storage Temperature Range ................... 65C to 125C T = 125C, = 76C/W, = 13.5C/W JMAX JA JC EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB ORDER PART NUMBER DDB PART MARKING LT3497EDDB LCGT Order Options Tape and Reel: Add TR Lead Free: Add PBF Lead Free Tape and Reel: Add TRPBF Lead Free Part Marking: